Recurrent aphthous ulcers, Behcet's disease and Sjogren's Syndrome are three disease states of unknown etiology with oral manifestations. Despite the frequency and severity of these disorders, very few attempts have been made to isolate viruses from patients with these diseases. The basic purpose of this study consists of the diagnosis and attempts to elicit chronic, slow or latent viruses from these patients. This approach will include attempts to demonstrate new antigens or antibodies in these patients.